Electric lamp.



me STATES ATENT Fries...

MARSHALL WILFRED HANKS, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGE WESTINGHOUSE, OF SAME PLACE.

ELECTRlC LAM P.

SPEGIFICATION forming part of Letters Patent N 0. 669,580, dated Mar h 12, 1901.

Applicationfiled June 7, 1900. Serial No. 19.383. (No model.)

To (tZZ whom it may concern:

Be it known that I, lVIARSHALL WILFRED HANKS, a citizen of the United States, resid' ing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electric Lamps, of which the following is a specification.

My invention relates to electric lamps the lightemittin'g bodies of which are non-couductive when cold and conductive when hot, and particularly to lamps of this character which employ several light-emitting bodies or glowers.

The object of my invention is to provide a simple and efficiently-operative means for insuring the lighting up of all of the glowers constituting the luminous element of the lamp, and also preventing the closing of the heater-circuit, and consequently the possible destruction of the heater, in case all of the glowers of the set should become destroyed by flashing out or otherwise.

With these ends in view I have devised the means shown in the accompanying drawing, the single figure of which is a diagram of a lamp and the work-circuit supplying energy thereto.

It is of great advantage in many cases to keep the heater in circuit a definite length of time after the first glower of the lamp lights up in order that all of the glowers may be utilized together. This is of special importance in connection with multiple glower lamps, in which the heater is automatically moved away from the glowers after the latter become conductive. Inasmuch as all the glowers of the set are not likely to be of exactly the same character as regards composition or dimensions or not disposed in exactly the same way with reference to the heater some of them will light up more quickly than others, and consequently if the heater is removed or cut out of circuit, or both removed and cut out as soon as a single glower lights up the remainder of the glowers will be of no use in the operation of the lamp. Furthermore, unless some special means is employed for keeping the heater out of circuit the case by reason of flashing out or from some other cause.

Referring to therlrawing, the lamp is shown as provided with three glowers 1, which are made as nearly alike as possible and are connected by means of the terminal wires 2 at one end and a common conductor 3 to one of the conductors 4 of the work-circuit. The other terminals of the glowers are connected through ballast resistances 5 and through suitable conductors 6 and 7 and conductor 8 to the other conductor 4 of the work-circuit. The heater 9 for glowers 1 may be permanently located in proximity to the glowers or it may be provided with means for removing it from the immediate vicinity of the glowers when the latter become heated to a conducting temperature, both forms of heater being known in the art. The circuit through the heater is by means of conductor 3, from. which connection is ma'de to one terminal of the heater by Wire 10 and conductor 11, and from the other terminal of the heater by stationary contact-terminals 12, corresponding movable terminal 13,and conductors 14 and 8. The terminal 13 of the cut-out is shown as mounted upon the core 15 of a solenoid 16, though any other suitable form of cut-out may be employed, if desired. One terminal of the solenoid 16 is connected to the conductor 8 and the other terminal is connected to one end of a controlling-glower 17 through conductor 18, ballast resistance 19, and conductor 20. The other terminal of the controlling-glower is connected to the terminal wire 3 by'a terminal wire 21. The controlling-glower 17 is made of such material or dimensions, or both, that it will not be heated to conducting temperature until a predetermined length of time after the glowers 1 have become conductive. It will also preferably be of lower efficiency than the glowers 1, so that while it may not give any considerable amount of light it will be substantially free from danger of destruction by reason of the current passing through it, and consequently it will always remain in service.

While I term this device a glower, it is not employed for the same purpose as are the glowers 1, and, in fact,as already indicated, it may not have any considerable or appreciable i1luminating power. It may not always be found necessary or advisable to employ a'steadying or ballast resistance in series with the glower 17, and when this is not employed the connection with the solenoid 16 maybe made as indicated by the broken line at 22. a

The operation of my invention is as follows: When the current is turned on, the heater cut-out is closed and the current will therefore traverse the heater until the glowers 1 become conductive and for as much time thereafter as is necessary to raise the temperature of the glowers 17 to the conductingpoint. When that point is reached, the current Will flow through the solenoid 16 to the glower 17 and the solenoid will obviously raise its core and open the heater-circuit. If the apparatus is properly constructed, the lighting up of all of the main glowers of the lamp will be insured. Furthermore, if all of the main glowers should be destroyed by reason of long use or accident the current flowing through the controlling-glower 17 would serve to keep the heater-circuit open, and thus prevent a needless waste of current and deterioration of the heater.

I desire it to be understood that my invention is not limited to the use of any specific number of glowers or to any specific construction of the several elements of the apparatus employed.

I claim as my invention- 1. An electric lamp of the class described having a plurality of glowers of approximately the same character and efticiency and a controlling-glower of lower efficiency, in combination with aheater and a cut-out thereling-glower connected in series with said coil and remaining non-conductive until after all the other glowers become conductive.

3. In an electric lamp of the class described, the combination with a plurality of glowers and a heater constructed and arranged to raise the temperature of said glowers to the conducting-point, of a controlling-glower requiring either a higher temperature or a longer period of heating to render it conductive and a heater cut-out having its actuating member connected in series with the controlling-glower.

4. In an electric lamp of the class described, the combination with a controlling-glowerand a heater, of a heater cut-out having its actuating member in series with said glower and a plurality of main glowers connected to the work-circuit in parallel with the cut-out actuator and the controlling-glower and constructed and arranged to become conductive in advance of the controlling-glower.

In testimony whereof I have hereunto subscribed my name this tth day of June, 1900.

MARSHALL WILFRED HANKS.

Witnesses:

MURRAY CHARLES BEEBE, EDWARD BENNETT. 

